Through the studies outlined here we hope to explore alterations in glycoprotein formation, structure and function in transformed and malignant cells. Emphasis will be placed on further investigation of a distinctive galactosyltransferase (designated galactosyltransferase isoenzyme II, GT-II) associated with both clinical malignancy and in vitro transformation. Both GT-II and a normal galactosyltransferase isoenzyme (GT-I) have been purified to homogeneity. We will explore amino acid sequence and carbohydrate chain structure determinations on the purified isoenzymes. We have now produced antibodies to human GT-I and GT-II and are in the process of developing a prototype radioimmunoassay to facilitate more extensive evaluation and widespread use of GT-II measurement as well as in situ localization of GT-II in the transformed cell. Studies with CEF infected with a temperature sensitive RSV should provide important data on the relationship of GT-II production (and secretion) to biological transformation as well as the isolation of the natural substrate of this enzyme. We will continue our studies of a previously described cancer-associated glycopeptide which serves as a cancer-associated galactosyltransferase acceptor (CAGA). This glycopeptide has been detected in sera of patients with extensive metastatic cancer. Purified CAGA specifically inhibits growth of transformed cells in culture and causes reduction of tumor growth in animal models. We have explored the kinetics of CAGA attachment to transformed cells with tritiated CAGA and are in the process of purifying the cellular CAGA-receptor from transformed CEF. In view of the effects of CAGA in vitro on glycoprotein composition and synthesis in transformed (CAGA-sensitive) cells, the effects of CAGA on intermediate carbohydrate metabolism are currently under investigation. The pharmacokinetic characteristics of CAGA, its mechanism of tumor growth inhibition and its potential use as an antineoplastic agent are being studied with a variety of animal tumor models.